Process of bleaching artificial silk.



UNITED STATES PATENT OFFICE.

CHARLES A. ERNST, LANSDOWNE, PENNSYLVANIA, ASSIGNOR TO SILAS W. PETTIT, OF PHILADELPHIA, PENNSYLVANIA. I

PROCESS OF BLEAOHING ARTIFICIAL SILK.

Specification of Letters Patent.

Patented Nov. 28, 1905.

Application filed July 8,1905. Serial No. 263,837.

T0 at whmn it may concern.-

Be it known that I, CHARLES A. ERNST, a citizen of the United States, and a resident of Lansdowne,county of Delaware,State ofPennsylvania, haveinvented certain new and useful Improvements in Methods of Bleaching and Finishing Artificial Silk Made from Viscose or Similar Material, of which the following is a full, clear, and exact description. I

My invention relates to the manufacture of artificial silk and filaments made from viscose, and has for its object the production of a whiter, cleaner, and stronger bleached filament or thread than has heretofore been produced by the methods of manufacture as now practiced.

Heretofore it has been attempted to bleach threads and filaments made from viscose by treating them for a longer or shorter period in bleaching solutions of various strengths; but it has been found that if the threads or filaments are left in the bleaching solution for a sufficient length of time to permit a weak bleaching solution to remove all the impurities or foreign coloringmatter contained therein or in a solution strong enough to remove all the said coloring-matter in a short time the threads have been so materially weakened as to make them unfit for many purposes, and if the threads or filaments are not permitted to remain in the bleaching solution so long as to affect the tensile strength thereof they are imperfectly bleached.

The objectionable coloring substance found in unbleached threads or filaments made from viscose are composed of or may be divided into two classesfirst, sulfur compounds remaining in the silk as residual products of the various steps by which the threads or filaments are produced, and, secondly, coloring substances which do not contain sulfur or sulfurous compounds.

In carrying out my invention I subject the unbleached threads or filaments made from viscose first to the action of a neutral agent or solvent, which effectively removes or changes these sulfur compounds, and then to the action of a second agent, more properly a bleaching agent, whereby the remaining impurities are removed.

My invention consists in the method hereinafter described in the specification and specified in the claims.

The operation of my process is as follows:

'poses.

The unbleached silk or filaments are first soaked in water to remove whatever foreign matter there may be adhering to the surface thereof and for the purpose of softening to a slight degree the viscose filaments or threads.

I then steep the artificial silk for one or two.

hours in a five-per-cent. neutral solution of a soluble oil, such as a sulfonated 0il-c. 9., Turkey-red oil-the temperature of which is maintained at substantially forty degrees centigrade, (4:0 C.) I then remove the artificial silk from said oil-bath and wash it in water to remove the oil. By this treatment I have found that the oil has a definite dissolving action upon the impurities composed of residual sulfur compounds arising from the process by which the artificial silk is produced, and that the silk at this step of the process is very much lighter in color and clearer than it was before it was immersed in the said oil, thus showing conclusively that some of the impurities have been removed as a result of the continued action of the soluble oil. Afterthis the silk is removed from the oilbath, and after the oil has been washed off in two warm waters the silk is passed into the bleaching solution proper, which is composed in the main of a solution of sodium hypochlorite. This bleaching solution operates to remove whatever coloringmatter remains in the silk and in a comparatively short time, although if a longer treatment is desired the solution may be made much weaker than heretofore used for similar pur- In other words, by subjecting the silk to a preliminary treatment whereby some of the impurities are removed by an agent which does not in any way affect or weaken the tensile strength of the threads or filaments I am enabled to remove whatever of coloringrmatter remains and has not been affected by the said oil by the use of a weak bleaching agent and in so short a time that the tensile strength of the threads or filaments is not materially weakened by the action of said solution. While I have found that a plain solution of sodium hypochlorite will perform the'functions and clearing effect above set forth, I preferably render the said bleaching solution slightly acid by adding thereto a small quantity of acetic acid. After treatment in the bleaching-bath as above described the silk is washed and dried in the usual manner.

I am aware thatit has been heretofore pro- I posed to use in connection with the bleaching agent various kinds of oil; but, so far as I can ascertain, the function of the oil in every instance is to form a protective coat or sheath around the strand of material to be bleached, so as to protect the material being bleachedas much as possible from the weakening effect of the bleaching solution, and to form this coating or sheath it has been proposed to immerse the goods for a short period of time-as, for example, for one or two minutes-in some protective oil; but, so far' as I am aware, I am the first to subject the strands or. threads or filaments of artificial silk to the. long and continued action of a sulfonated oil for the purpose of dissolving out of the silk and; into the oil the residual sulfur compounds. The immersion of the silk for one or two minutes in an oil or a soluble oil has no appreciable whitening effect on the silk, nor does it shorten the length of time the material has to remain in the. bleaching solution, the result being a very difierent one when the silk is subjected for a long time to the action of the oil.

WhatIclaim as my invention and desire to cover by Letters Patent, is

1 The process of bleaching artificial silk made of filaments of viscose or similar material consisting of subjecting the, same to the action ofsoluble oil for removing the sulfur compounds, and secondly, to the action of a solution of a bleaching-salt.

2. The process of bleaching artificial silk made of filaments of viscose or similar material consisting of removing the sulfur coloring composition by subjecting the silk to the action of a soluble oil and afterward to the action of a solution of sodium hypochlorite.

3. The process of bleaching artificial silk made from filaments of viscose or similar material, consisting of removing the sulfur coloring compound by subjecting the silk to an action of a sulfonated oil and afterward to the action of a solution of sodium hypochlorite.

4. The process of bleaching artificial silk made of filaments of viscose or similar material consisting of removing the sulfur coloring-matter contained by subjecting the silk to the action of Turkey-red oil and afterward immersing the Silk in a solution of sodium hypochlorite.

5( The process of bleaching artificial silk made of filaments of viscose or similar material consisting of steeping the silk in Turkeyred oil, and secondly, removing other remaining impurities by subjecting the silk to a suita'ble bleaching solution.

6. The process of bleaching artificial silk made of filaments of viscose or similar mate rial consisting of steeping the silk in a bath of Turkey-red oilat a temperature of substantially 40 centigrade; which acts to dissolve the sulfur coloring impurities, and of removing the remaining impurities by subjecting the silk to the action of a suitable bleaching solution.

7. The process of bleaching artificial silk made of'filaments of viscose or similar material consisting of subjecting the silk to the continued action of a soluble oil at a temperature of substantially 40 centigrade and afterward subjecting the same to the action of a suitable bleaching solution.

8. The process of bleaching artificial silk made of filaments of viscose or similar material consisting of subjecting the silk to the action of a soluble oil to remove the sulfur impurities, washing the silk to remove the adhering oil, and then subjecting the silk to the action of a bleaching solution composed substantially of sodium hypochlorite.

9. The process of bleaching artificial silk made of filaments of viscose or similar material consisting of subjecting the sillbto the continued action of a soluble oil to rerfi e the sulfur coloring compounds and afterw hlf bleaching the same in an acid solution of sodium hypochlorite.

10. The process of bleaching artificial silk made of filaments of viscosev or similar material consisting of subjecting the silk to the continued action of a sulfonated oil at'a temperature of substantially 40 centigrade and afterward subjecting the same to the action of a suitable bleaching solution.

11. The process of bleaching artificial silk made of filaments of viscose or similar material consisting of subjecting the silk to the action of a sulfonated oil to remove the sulfur impurities, washing the silk to remove the adhering oil, and then subjecting the silk to the action of a bleaching solution composed substantially of sodium hypochlorite.

12. The process of bleaching artificial silk made of filaments of viscose or similar material consisting of subjecting the silk to the continued action of a sulfonated oil to remove the sulfur coloring compoundsand afterward bleaching the same in an acid solution of sodium hypochlorite.

13. The process of bleaching artificial silk made of filaments of viscose or similar material consisting of steeping the silk in a solution of Turkey-red oil to remove the soluble sulfur compounds, and then bleaching the same in a Weak acid solution of sodium hypochlorite.

14. The process of bleaching artificial silk made of filaments of viscose or similar material consisting of steeping the silk in a solution of Turkey-red oil at substantially 410 centigrade, and secondly, bleaching the same in a weak solution of sodium hypochlorite, to which has been added a small quantity of acetic acid.

15. The process of bleaching artificial silk made of filaments of viscose or similar material consisting of soaking the artificial silk in water, secondly, steeping the same in a five- IIO per-cent. neutral solution of Turkey-red oil to remove the sulfur impurities, washing the same in warm Water to remove the adhering oil, subjecting the silk to the action of a bleaching solution composed of a weak solution of sodium hydrochlorite and acetic acid, Washing in clear water to remove the said bleach and drying the same.

16. The preparatory step in the bleaching of filaments made from viscose which consists in first subjecting the silk to the continued action of a neutral solution of Turkey-red oil for the purpose of removing or dissolving out sulfur coloring compounds.

17 The process for removing the objection I5 able sulfur coloring. compounds of unbleached artificial silk, consisting of steeping the silk in a five-per-cent. solution of Turkey-red oil.

In witness whereof I have hereunto set my hand this'5th day of July, A. D. 1905.

CHARLES A. ERNST.

Witnesses:

HORACE PETTIT, ALEXANDER PARK. 

